Directional Control Valve Block - M8- 2021

https://www.facebook.com/M.Naguib.fouda Directional Control Valve- M8 Compact valve blocks, series M8 are primarily used for the control of standard functions in track driven and wheeled excavators, such as arms, buckets, transmission, dipper and slew (swing) within a 2 circuit hydraulic system. They may even be usefully used in drilling devices and cranes. Compact valve block M8 replaces the previous 4 axis valve blocks in 2 circuit controls. The advantage of this type over a separated design lies in the reduced time and effort required for assembly and piping. Technical features – Valve control to the 6/3 way principle – Proportional control characteristic – Further fine control range for sensitive flow control – Hydraulic control by means of pilot operated device type TH, electrical control available on request Spool stroke, control characteristics The spool stroke is divided into appox. 30 % control land overlap, approx. 50 % fine control range and approx. 20 % residual stroke for creating fully opened cross-section. Optimum fine control is achieved by means of the fine control grooves in the pilot devices. Deceleration spool These are used in hydrostatic transmissions in tracked vehicles and are used to avoid the over-running of the drive in both directions of travel. Controlled, cavitation-free downhill travel is achieved by control Function, circuit diagram for excavator valve block The block mainly comprises the housing, the control spool with return springs (1), built-in primary cartridge valves (3) and secondary cartridge valves (4), as well as load holding valves (2). Connected to pump P1 (5) are usually arm (12, spool axis 1) and bucket (13, spool axis 2), as well as transmission L (14, spool axis 3). Arm and bucket may be supplied with fluid either in parallel or in series, i.e. both functions may be carried out simultaneously. If these functions are not used, the pump flow is available for control of the transmission. Pump P2 (6) usually supplies the slew (17, spool axis 7), dipper (16, spool axis 6) and transmission R (15, spool axis 5). The slew has priority over the dipper and transmission (tandem circuit). The dipper function has priority over the transmission. Flow from pump P2 not required for these functions may [by operating the C valve (10)] be used for the external summation with another actuator. If neither arm, bucket nor transmission L (spool axes 1-3) are operated, flow from pump P1 may be made available by internally activating the summation valve (9) of spool axis 6 (control of dipper) (dipper summation). By means of the transmission compensation valve (7) the remaining of oil from pumps P1 and P2 may be combined for the supply of both spool axes for the transmisssions. Hence various operations may be carried out during travel, without the vehicle deviating from its path of travel. If only the transmission spools are operated, the transmission compensation valve is then at rest and only a residual compensation is carried out. Preload valves (11) arranged in the return cause the return oil to be divided between the cooler and tank. The return oil which has built up may only be removed via port “S” and then fed to the slew motor for the purpose of anti-cavitation. In addition to the model of the compact valve block described here, further variations exist, which our project department MH-V is willing to provide information on. Similary help is provided for the design of hydraulic controls using M8 valve blocks. #Directional_Control_Valve_Block_M8 #Hydraulic_Valves